Mold for sound-records.



T. A. EDESUN.

MOLD FOR SOUND RECORDS. APPLICATION FILED 001.13.1914.

Patented Dee. 30,1919.

UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, 0F LLEWELLYN PARK, WEST ORANGE, NEW JERSEY, ASSIGNOR T0 v NEW JERSEY PATENT COMPANY, OF WEST ORANGE, NEW JERSEY, A CORPORATION 0F N JERSEY.

MOLD FOR SOUND-RECORDS.

Specicationof Letters Patent. Patented Dec. 30, 1,919.

Original application led .Tune 10, 1911, Serial No. 632,366. Divided and this application filed October 13, 1914. Serial No. 866,437.

To all whom t may concern:

Be it known that I, THOMAS A. EDISON, a citizen of the United States, and a resident of Llewellyn Park, West Orange, in the county of Essex and State of New Jersey, have invented certain new and useful lmprovements in Molds for Sound-Records, of which the following is a description.

My invention relates to molds for sound records, particularly those of the disk type, this application'being a division of my application, Serial No. 632,366, filed June 10, 1911, upon which United States Patent No. 1,118,114 has been granted. lnv forming these molds, it is common to coat the original wax record with a covering of graphite to render its surface electro-conductive, then to place it in an electro-plating bath and deposit a thin layer of copper thereon by electrolysis. The copper electrotype or matrix thus formed is then separated from the waxlike original record and backed up in any suitable way to give the same sufficient rigidity for use as a stamp or die to impress the record intothe record material. It has heretofore been common to secure the back! ing, which is commonly made ofmetal, to the electrotype or matrix by soldering the said parts together overv substantially the whole of the contacting surfaces. This method of securing the matrix or electrotype to the backing is objectionable as in nearly every case the soldering is uneven so that an uneven surface 1s produced 1n the matrix and 1n the record formed therefrom when said parts are subjected to the great pressure necessary to impress the record into the plastic material from which the duplicates are to be formed. The unevenness of the record produced in this way is the cause of some of the noises which are emitted when the record is reproduced.

It is the object of my invention to obviate the above named objection and to produce a mold which is strong and capable of producing an exact duplicate of the Original sound record. Broadly, my invention consists 1n securing the matrix or electrotypeto the backing in an improved way obviatmg the necessity of soldering the whole of the two adjacent or contacting' surfaces thereof. This may be accomplished by finishing 1n l then securing the same together at their edges.

In order that my invention may be more fully understood, attention is hereby directed to the accompanying drawings forming' a part of this specification, and in which- Figure 1 represents a central vertical section of the original master recordwith the electro-deposited matrix thereon;

'Fig. 2 represents a similar View showing the matrix mounted upon a suitable supportor holder for use during the finishing of the rear or reverse surface thereof;

Fig. 3 represents a similar view of a completed mold embodying my invention; and

Fig. 4 represents a similar view of a modied form of mold.

In all of the views, like parts are designated by the same reference numerals.

Referring to the drawing, the numeral l represents the wax master record upon which the matrix 2 has been formed, as by elec trolysis, in a copper bath. The outer surface of the matrix, as shown in Fig. l, is

.more or less rough when removed from the bath. After detaching the electrotype or matrix from the master, I provide the same with a facing 3 of soft material, such as blotting paper or the like, and secure the flange 2 at the edge thereof upon a holder 4 in any suitable way, as by means of screws 5. As shown in Fig. 2, a bolt 6 is passed through alined openings in the center of the matrix 2, the facing 3, and the holder 4f and is provided with nuts 7, 7 whereby it is adapted to assist in. clamping the matrix to the holder. The numeral 8 designates a washer interposed between the bottom of the holder 4 and the upper nut 7. The matrix 2, having been secured to the holder, is finished yto a true surface, as by turning the same in a lathe and then polishing the sur- 100 face thereof.

After the backing 9 has been likewise turned true and polished, the matrix and the backing are superposed with their finished surfaces in contact and are subjected to pressure to force them into firm engagement with each other. The flange 2. on the matrix is then remove-d, as by -cuttlng the same away in a lathe, or in any other suitable way, after which the edges of the matrix and backing are secured together'. In one construction, I spin the outer edge or periphery of the electrotype or matrix over the edge of the backing and into the shallow oove or depression 10 in the backing;

ut it is evident that the edges of the` matrix and backing may be secured to each ing the said ring to loosen or tighten the same. A sleeve 15 provided with a ange 16 seated in a depression in the top of the matrix is threaded to the center of the backing and assists in securing the matrix in place. I prefer to make the backing 9 of steel and the plate 11. of cast iron, the contacting surfaces of these parts being ground true but not polished. The opposlng faces of the matrix and backing are turned and polished as described above.

The polish and trueness of the opposing surfaces ofthe matrix and backing need not be as great as is necessary when the surfaces are directly'in contact with each other if a sheet 17 oftin'foil or other yielding material is laid between the opposing faces' of the matrix and backing as shown in Fig.v 4,-

suc'h material yielding under the molding pressure and conforming readily to the slight irregularities in the said faces. This foil or equivalent materiall should, however, be very thin preferably no thicker than about .005 ofan inch in o-rder to prevent flowing of the same under the high pressures used in molding records of the commonly employed plastic material. It is 'evident that this foil may be used in all forms of my invention regardless of the particular method employed for securing together the edges ofthe matrix and backing. The

numeral 18 designates a pin secured to the center of the mold and adapted to center the blank in which the record is to be stamped.

While I have shown my invention as applied to disk records, it is evidently applicable to cylindrical records as well. The finishing of the opposing surfaces of the matrix and 4backing may be accomplished in any suitable way and numerous modifications maybe made without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent is as follows:

1. A mold for sound records ycomprising a matrix and backing pressed toward each other, secured together and having their adjacent faces trued and polished to forms litting each other evenly, whereby the formation of irregularities 0n the outer face of the matrix is prevented, substantially as described.

2, A mold for sound records comprising a matrix, a backing, and a thin sheet of yielding material interposed between said matrix and backing, substantially 'as described.

3. A mold for sound `records comprising a matrix, a backing, and a thin sheet of yielding material interposed between said matrix and backing, the said matrix' and backing being secured together at their edges but not ,between their centers and peripheries, substantially as described. l

4. A mold for sound records comprising a matrix, a backing, and a thin sheet of tin- -foil interposed between said -matrix and backing, the said matrix and .backing being secured together at their edges but notv between their centers and peripheries, substantially as described.

` 5. A mold for sound records comprising a matrix, a backing, yielding material interposed Ibetween said matrix and backing, and a ring co-acting with the peripheries of said matrix and backing for securing the same together, substantially as described.

6. A mold for sound records comprising a matrix, a backing, and yielding material interp'osed between said matrix and backing substantially as described. 1

This specification signed and witnessed this 9th day of October, 1914.

THOS. A. EDISON.

Witnesseth: v

FREDERICK BAGHMANN, MARY J. LAIDLAW. 

